Revealing mistake: When the Hind helicopter first appears you can see that the rocket tubes are empty, yet Rambo later fires several rockets from them.
Suggested correction: Rambo never flies the Hind.

Continuity mistake: In the POW camp, Co Bao is discovered by a guard who points a handgun at her. Rambo shoots an arrow into the guard's forehead, who then falls back against a tree with his cap down low over his eyes. In the next shot his cap is much higher on his head, and the arrow is pointing at a different angle. How could his cap have moved up that far with the arrow holding it to his forehead? For that matter, how could the arrow have moved when it was firmly embedded in the guard's skull? (00:33:25)
Suggested correction: The arrow was able to move because upon piercing the skull, the arrow penetrated the brain, a soft matter that would not hold the arrow in place. The brain matter is much softer than flesh. Imagine shooting an arrow into a watermelon. It is not fixed, but moveable.
But the point of the arrow is sticking in the tree. If it wasn't the guard would have fallen to the ground. So it shouldn't have moved.
lionhead